Mothballs are small solid pesticides that slowly release toxic gas to kill clothes moths and their larvae. They contain very high concentrations of either naphthalene or paradichlorobenzene, and they’re designed to be used only inside sealed, airtight containers. Despite how casually many people treat them, mothballs are registered pesticides with real health risks to humans and pets when used incorrectly.
How Mothballs Work
A mothball doesn’t kill moths on contact. Instead, it gradually transitions from a solid to a gas through a process called sublimation. When placed inside a sealed container with clothing, those fumes build up to a concentration high enough to kill clothes moths, their eggs, and larvae. This only works in an airtight space. If the container isn’t sealed, the gas simply escapes into your living area without ever reaching a lethal concentration for the insects.
The two active chemicals used in U.S. mothballs are naphthalene and paradichlorobenzene (sometimes labeled PDB). Naphthalene is the older, more traditional ingredient with the stronger, more recognizable smell. Paradichlorobenzene is slightly less toxic to humans but still hazardous. Some older or imported mothballs contain camphor, which is considered the most toxic of the three to animals.
Health Risks for People
Naphthalene damages red blood cells, changing them so they can no longer carry oxygen effectively. This can lead to organ damage with significant exposure. Symptoms of poisoning may not appear for up to two days and can include abdominal pain, nausea, vomiting, and diarrhea. More severe exposure can cause jaundice (yellowing of the skin), blood in the urine, confusion, seizures, rapid heart rate, and dangerously low blood pressure.
People with a genetic condition called G6PD deficiency are especially vulnerable. Their red blood cells lack the protective mechanisms needed to handle the oxidative stress naphthalene creates. Even relatively small exposures can trigger a severe breakdown of red blood cells, leading to dangerous anemia. G6PD deficiency affects roughly 400 million people worldwide and is more common in people of African, Mediterranean, Middle Eastern, and Southeast Asian descent. Many people don’t know they carry it until an exposure like this triggers a crisis.
Children face the highest risk of accidental poisoning because mothballs can look like candy or toys. Chronic, low-level exposure from mothballs left in open spaces or closets without proper sealing is also a concern, as the fumes accumulate in indoor air over time.
Risks to Dogs and Cats
Pets are highly susceptible to mothball poisoning, and cats are thought to be more sensitive than other species. A single mothball can be enough to cause serious illness in a small dog or cat. The signs depend on which chemical the mothball contains, but exposure to any type typically causes vomiting, loss of appetite, abdominal discomfort, and lethargy.
With naphthalene mothballs, vomiting and appetite loss usually appear first, potentially followed by destruction of red blood cells, pale gums, difficulty breathing, and in rare cases, tremors or seizures. Paradichlorobenzene exposure primarily causes abdominal pain, vomiting, lethargy, and trembling. Repeated or large exposures to PDB can damage the liver and kidneys. Camphor-based mothballs are the most immediately dangerous, causing neurological symptoms including altered behavior, depression, and seizures.
If your pet chews or swallows a mothball, it’s a veterinary emergency. Vomiting can be induced up to four hours after ingestion, but only before neurological symptoms appear. Animals showing signs of poisoning typically need hospitalization with IV fluids and supportive care.
Legal Use: What the Label Requires
Using mothballs in any way not specified on their label is illegal under federal pesticide law. Labels direct users to place mothballs inside tightly closed, airtight containers to prevent fumes from accumulating in living spaces. That means a sealed plastic bin or a garment bag that zips completely shut, not an open closet, dresser drawer, or room.
One of the most common misuses is scattering mothballs outdoors to repel snakes, rodents, cats, or other animals from gardens and yards. This is both illegal and ineffective. Mothballs used outside contaminate soil, plants, and water, and the fumes never reach a concentration high enough to repel wildlife. They simply poison the environment while putting children, pets, and other animals at risk of direct contact.
Safer Alternatives That Actually Work
Cedar is one of the most effective natural moth deterrents. Its aromatic oils disrupt moth behavior at a neurological level, making it difficult for them to lay eggs or remain near treated areas. Research confirms cedar’s effectiveness against clothes moths as well as flour beetles, cockroaches, and ants. The catch is that cedar loses potency as it dries out, so you’ll need to replace cedar blocks or rings every few years, or lightly sand them to refresh the surface oils.
Lavender works through a similar mechanism. Sachets filled with dried lavender or treated with lavender essential oil repel moths effectively. Give sachets a gentle squeeze periodically to release more of their oils, and replace them once the scent fades noticeably.
Pheromone traps offer a different approach. They use synthetic moth attractants to lure adult males away from your clothing, interrupting the breeding cycle. Each trap lasts about three months before it needs replacing. These won’t kill larvae already in your clothes, but they’re excellent for monitoring and reducing moth populations.
The single most effective strategy is airtight storage. If wool, silk, or other vulnerable fabrics are sealed in plastic bins with tight-fitting lids, moths simply cannot reach them. Combining sealed storage with cedar or lavender inside the container gives you two layers of protection, which is the best approach for valuable or hard-to-replace garments.
Removing Mothball Smell
Mothball odor clings stubbornly to fabrics, furniture, and indoor spaces because the chemicals absorb into porous materials. Getting rid of it takes patience and a multi-step approach.
For rooms and homes, start by opening windows and using fans to push contaminated air out. This alone can take days or weeks depending on how long mothballs were present. Sprinkle baking soda on carpets, upholstered furniture, and other soft surfaces, leave it for 24 hours, then vacuum thoroughly. Baking soda’s porous structure traps and neutralizes odor molecules. Open bowls of baking soda, activated charcoal, or coffee grounds placed around the room will continue absorbing residual fumes over several days. An air purifier with both a HEPA filter and an activated carbon filter can help clear airborne chemical residue more quickly.
For clothing, start by airing items outdoors or in a well-ventilated space. Then wash them with a cup of baking soda or white vinegar added to your regular detergent. For shoes, pack baking soda inside overnight and shake it out before wearing. Wooden furniture responds well to wiping down with a solution of equal parts vinegar and water, followed by placing activated charcoal or coffee grounds nearby to absorb lingering odor.